The present invention relates generally to conduit couplings for fluid containing cylinders. More particularly, the invention relates to LP gas conduit couplings that include a fuse for automatic disconnection in the event of fire or potential fire.
Traditional LP gas valve connectors have used a P.O.L. nipple surrounded by a left hand nut. Generally, the nut threads into the outlet section of the cylinder valve with a 0.880xe2x80x3 thread at 14 threads/inch.
Many LP gas valve connectors now have included a heat sensitive nut to couple the nipple to the gas cylinder. The nut is designed to fail if the temperature reaches a temperature that could cause or indicate fire. Disconnection of the fluid-carrying conduits triggers an interruption in the fluid flow path. The interruption of the fluid flow path halts the flow of fuel, such as LP gas, to the heat source to prevent or reduce the possibility of fire.
The heat sensitive nut may be exposed to direct sunlight. This exposure to sunlight has caused such nuts to soften unevenly or in some cases fail. Such softening may distort the assembly producing premature decoupling or interruptions in fluid flow. It may also cause misalignment between the nipple and the nut creating problems in coupling and decoupling. Thus, a need existed to prevent direct exposure to sunlight of the heat sensitive material in the coupling.
Other couplings have been designed where only a portion of the nut is made of a heat sensitive material. At the very least, those systems require that the nut be replaced once the system fails. Thus, a need exists to reduce replacement costs for such systems.
The present invention includes a coupling system comprising a nipple, a check valve, a nut rotatably disposed around the nipple, and a fuse disposed around the nipple between the nut and the fluid entry end of the nipple. The fuse is composed of a heat sensitive material.
The fuse is configured to deform when subject to heat to ensure that the check valve is triggered closing off the flow of fluid. Furthermore, there is no need to replace the nut after failurexe2x80x94only the fuse must be replaced. The present invention reduces and in some case eliminates misalignment between nut and nipple because of its long, direct guiding surface contact between nipple and nut.